It is well known that nuclear fission has been utilized for electric power generation for over fifty years. As a process nuclear fission involves breaking apart larger atoms which in turn leads to smaller atoms. These smaller atoms are generally radioactive and some exhibit half-lives that are greater than 200,000 years such as tin-126, for example. A few others have even longer half-lives which can exceed 10 million years such as iodine-129, for example (Wikipedia: long-lived fission product. [accessed 2015 Feb. 18]. http://en.wikipedia.org/wiki/Long-lived_fission_product). These radioactive materials with half-lives in excess of 200,000 years are commonly referred to as high level waste (HLW). Because the half-lives are so long these materials represent a human health hazard requiring isolation for many hundreds of thousands of years. The United States (U.S.) has sought a technical, cost effective, environmentally and publicly acceptable solution to the storage of this material since the 1970s. At present there are well over 250 million pounds of HLW in the U.S. alone. In the late 2000s Yucca Mountain was approved by the Department of Energy (DOE) but subsequently the Obama administration suspended the license. As it stands the Yucca Mountain complex design was designated Environmental Protection Agency (EPA) compliant for a mere 10,000 years (U.S. Department of Energy Office of Civilian Waste Management. Analysis of the System Life Cycle Cost of the Civilian Radioactive Waste Management Program, Fiscal Year 2007. Washington, D.C.; July 2008. Report DOE RW-0591 & Blue Ribbon Commission on America's Nuclear Future. Disposal Subcommittee Report to the Full Commission Updated Report. Washington D.C.; January 2012.).
The Yucca Mountain plans call for a 100 year period of observation of the HLW after which all openings to the surface will be backfilled. However, the Yucca Mountain plans for activities after 100 years are unplanned other than to establish a plan at that time for the remaining million or so years that the HLW will need to be safe guarded (U.S. Department of Energy Office of Civilian Waste Management. Analysis of the System Life Cycle Cost of the Civilian Radioactive Waste Management Program, Fiscal Year 2007. Washington, D.C.; July 2008. Report DOE RW-0591).
Another proposed option for long term storage of HLW is for disposal in space. This option was studied in the 1970s and it was concluded that the option was technically viable but the costs were prohibitive and the environmental risks associated with a failed launch too great for large scale launch of radioactive HLW (Coopersmith J. Disposal of High-Level Nuclear Waste in Space. 1999: Space Studies Institute). However, radioactive material has been launched into space (but only as an auxiliary component of other much larger payloads) and stored there in the form of Radioisotope Thermoelectric Generators (RTG) used to power various deep space probes. The material commonly used to power those RTGs is plutonium-238 with fuel quantities around 2 pounds to just over 15 pounds. For example, the Mars Curiosity Rover utilizes a fuel that contains roughly 9 pounds of plutonium-238. In addition, for the small radioactive RTGs U.S. launch accidents have occurred without contamination and current cask container design has been thoroughly studied for this particular hazard (Wikipedia: Radioisotope thermoelectric generator. [accessed 2014 Nov. 06]. http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator).
Hence, at present there exists no viable option for long term storage of radioactive HLW and as such the waste is generally stored where it is produced, such as reactor stations, awaiting a solution. What is needed is a viable option to solve this issue that grows every day. The present patent disclosure provides for a solution in that the radioactive HLW is permanently removed from the Earth using a payload delivery system. The payload delivery system solves the technical problem of long term storage and in addition solves the environmental and public concerns associated with launch risk by use of a small payload of a few pounds, for example. In addition the small payload solves other problems with space storage of radioactive HLW (environmental and public acceptance) and with economics of mass production could eventually reduce the costs to an acceptable level. The solution to the problem in this disclosure can also act as starting point eventually leading to the launching of successively larger and larger payloads and thereby overcome the economics of space disposal of radioactive HLW.
The present disclosure concerns small payloads (e.g., less than 10 pounds) which typically require small rocket stages as part of the payload delivery system. However, conventional small rocket stages often have a very low propellant mass fraction, an inefficiency which leads to lower deliverable payload mass. Conventional payload delivery systems involving rocket stages often carry different propellants to serve different functions within a rocket stage. For example, the German V-2 rocket was a single stage rocket system which utilized liquid oxygen as oxidizer and ethanol as liquid fuel in the stage main propulsion engine. In addition, liquid hydrogen peroxide decomposition (by liquid permanganate solution) was used to drive the turbopumps, and pressurized gaseous nitrogen was used as the pressurant for each of the aforementioned liquids (National Museum of the US Air Force: U.S. Army cut-away of the V-2. [accessed 2015 Apr. 30]. http://www.nationalmuseum.af.mil/shared/media/photodb/photos/090928-F-1234S-011.jpg,). In all, the German V-2 single stage rocket system used five different propellants. Use of multiple propellants with conventional rocket stages, such as the German V-2, lead to lower propellant mass fraction and hence lower delivered payload generally because all the different propellants require tanks, valves and other control devices. In fact, use of conventional propellants in small stages has such a low propellant mass fraction that the overall system may not be able to deliver the required payload. What is needed is a small rocket stage that uses a minimum amount of propellants. In contrast to conventional rocket stages, use of a single propellant to perform all of the functions on a stage, for example, can permit minimization of tanks and handling apparatus; such minimization directly translates into a reduced inert mass of a stage, which then directly translates into a high propellant mass fraction and further into higher deliverable payload mass. This minimization of tanks, etc. is especially critical for small-sized rocket stages. Examples of single liquid propellant self-pressurization configurations which would be subsystems of a single liquid propellant stage using the monopropellants of hydrazine and hydrogen peroxide are provided by Whitehead, Whitehead et al. and Ledebuhr et al. (Whitehead J C, Pittenger L C, Colella N J. ASTRID Rocket Flight Test. Lawrence Livermore National Labs Energy & Technology Review. July 1994 [accessed 2015 Apr. 29]; https://str.llnl.gov/etr/pdfs/07_94.2.pdf), (Whitehead J C. Self Pressurizing HTP Feed Systems. 2nd International Hydrogen Peroxide Propulsion Conference; 1999 Nov. 7-10; West Lafayette, Ind. Lawrence Livermore National Labs Report UCRL-JC-136124) and (Ledebuhr A G, Antelman D R, Dobie D W et al. Recent Development in Hydrogen Peroxide Pumped Propulsion. 2nd Missile Defense Conference and Exhibit: 2004 Mar. 22-26; Washington, D.C. Lawrence Livermore National Labs Report UCRL-CONF-203137).